使用 C++ 類進行封裝的 SQLite3

SQLite C++ · 發表 2018-09-28 14:00:09

摘要： sqlite3pp 該庫對SQLite3 API使用C++類進行包裝，支援幾乎所有SQLite3功能（開啟資料庫、查詢、執行命令、事物等）。示例程式碼如下： database 資料庫 sqlite3pp::database db(&#...

sqlite3pp

該庫對SQLite3 API使用C++類進行包裝，支援幾乎所有SQLite3功能（開啟資料庫、查詢、執行命令、事物等）。

示例程式碼如下：

database 資料庫

sqlite3pp::database db("test.db");
db.execute("INSERT INTO contacts (name, phone) VALUES ('Mike', '555-1234')");

command 命令

sqlite3pp::command cmd(
db, "INSERT INTO contacts (name, phone) VALUES (?, ?)");
cmd.binder() << "Mike" << "555-1234";
cmd.execute();
sqlite3pp::command cmd(db, "INSERT INTO contacts (name, phone) VALUES (?, ?)");
cmd.bind(1, "Mike", sqlite3pp::nocopy);
cmd.bind(2, "555-1234", sqlite3pp::nocopy);
cmd.execute();
sqlite3pp::command cmd(
db, "INSERT INTO contacts (name, phone) VALUES (?100, ?101)");
cmd.bind(100, "Mike", sqlite3pp::nocopy);
cmd.bind(101, "555-1234", sqlite3pp::nocopy);
cmd.execute();
sqlite3pp::command cmd(
db, "INSERT INTO contacts (name, phone) VALUES (:user, :phone)");
cmd.bind(":user", "Mike", sqlite3pp::nocopy);
cmd.bind(":phone", "555-1234", sqlite3pp::nocopy);
cmd.execute();
sqlite3pp::command cmd(
db,"INSERT INTO contacts (name, phone) VALUES (:user, '555-0000');"
"INSERT INTO contacts (name, phone) VALUES (:user, '555-1111');"
"INSERT INTO contacts (name, phone) VALUES (:user, '555-2222')");
cmd.bind(":user", "Mike", sqlite3pp::nocopy);
cmd.execute_all();

transaction 事務

sqlite3pp::transaction xct(db);
{
sqlite3pp::command cmd(
db, "INSERT INTO contacts (name, phone) VALUES (:user, :phone)");
cmd.bind(":user", "Mike", sqlite3pp::nocopy);
cmd.bind(":phone", "555-1234", sqlite3pp::nocopy);
cmd.execute();
}
xct.rollback();

query 查詢

sqlite3pp::query qry(db, "SELECT id, name, phone FROM contacts");for (int i = 0; i < qry.column_count(); ++i) {
cout << qry.column_name(i) << "\t";
}
for (sqlite3pp::query::iterator i = qry.begin(); i != qry.end(); ++i) {for (int j = 0; j < qry.column_count(); ++j) {
cout << (*i).get<char const*>(j) << "\t";
}
cout << endl;
}
for (sqlite3pp::query::iterator i = qry.begin(); i != qry.end(); ++i) {int id;char const* name, *phone;std::tie(id, name, phone) =
(*i).get_columns<int, char const*, char const*>(0, 1, 2);
cout << id << "\t" << name << "\t" << phone << endl;
}
for (sqlite3pp::query::iterator i = qry.begin(); i != qry.end(); ++i) {
string name, phone;
(*i).getter() >> sqlite3pp::ignore >> name >> phone;
cout << "\t" << name << "\t" << phone << endl;
}
for (auto v : qry) {
string name, phone;
v.getter() >> sqlite3pp::ignore >> name >> phone;
cout << "\t" << name << "\t" << phone << endl;
}

attach

sqlite3pp::database db("foods.db");
db.attach("test.db", "test");

sqlite3pp::query qry(
db,"SELECT epi.* FROM episodes epi, test.contacts con WHERE epi.id = con.id");

backup 備份

sqlite3pp::database db("test.db");
sqlite3pp::database backupdb("backup.db");

db.backup(backupdb);
db.backup(
backupdb,
[](int pagecount, int remaining, int rc) {
cout << pagecount << "/" << remaining << endl;if (rc == SQLITE_OK || rc == SQLITE_BUSY || rc == SQLITE_LOCKED) {// sleep or do nothing.}
});

callback 回撥

struct rollback_handler{void operator()() {
cout << "handle_rollback" << endl;
}
};

sqlite3pp::database db("test.db");

db.set_commit_handler([]{ cout << "handle_commit\n"; return 0; });
db.set_rollback_handler(rollback_handler());
int handle_authorize(int evcode, char const* p1, char const* p2,char const* dbname, char const* tvname) {
cout << "handle_authorize(" << evcode << ")" << endl;return 0;
}

db.set_authorize_handler(&handle_authorize);
struct handler{handler() : cnt_(0) {}void handle_update(int opcode, char const* dbname,char const* tablename, int64_t rowid) {
cout << "handle_update(" << opcode << ", " << dbname << ", " << tablename << ", " << rowid << ") - " << cnt_++ << endl;
}int cnt_;
};using namespace std::placeholders;db.set_update_handler(std::bind(&handler::handle_update, &h, _1, _2, _3, _4));

function

int test0()
{return 100;
}

sqlite3pp::database db("test.db");
sqlite3pp::ext::function func(db);

func.create<int ()>("test0", &test0);
void test1(sqlite3pp::ext::context& ctx)
{
ctx.result(200);
}void test2(sqlite3pp::ext::context& ctx)
{
string args = ctx.get<string>(0);
ctx.result(args);
}void test3(sqlite3pp::ext::context& ctx)
{
ctx.result_copy(0);
}

func.create("test1", &test1);
func.create("test2", &test2, 1);
func.create("test3", &test3, 1);
func.create<int ()>("test4", []{ return 500; });
string test5(string const& value)
{return value;
}

string test6(string const& s1, string const& s2, string const& s3)
{return s1 + s2 + s3;
}

func.create<int (int)>("test5", [](int i){ return i + 10000; });
func.create<string (string, string, string)>("test6", &test6);
sqlite3pp::query qry(
db,"SELECT test0(), test1(), test2('x'), test3('y'), test4(), test5(10), "
"test6('a', 'b', 'c')");

aggregate

void step(sqlite3pp::ext::context& c)
{int* sum = (int*) c.aggregate_data(sizeof(int));

*sum += c.get<int>(0);
}void finalize(sqlite3pp::ext::context& c)
{int* sum = (int*) c.aggregate_data(sizeof(int));
c.result(*sum);
}

sqlite3pp::database db("foods.db");
sqlite3pp::ext::aggregate aggr(db);

aggr.create("aggr0", &step, &finalize);
struct mycnt{void step() {
++n_;
}int finish() {return n_;
}int n_;
};

aggr.create<mycnt>("aggr1");
struct strcnt{void step(string const& s) {
s_ += s;
}int finish() {return s_.size();
}
string s_;
};struct plussum{void step(int n1, int n2) {
n_ += n1 + n2;
}int finish() {return n_;
}int n_;
};

aggr.create<strcnt, string>("aggr2");
aggr.create<plussum, int, int>("aggr3");
sqlite3pp::query qry(
db,"SELECT aggr0(id), aggr1(type_id), aggr2(name), aggr3(id, type_id) "
"FROM foods");

loadable extension 載入擴充套件

#define SQLITE3PP_LOADABLE_EXTENSION#include <sqlite3ppext.h>int sqlite3_extension_init(
sqlite3 *pdb,char **pzErrMsg,const sqlite3_api_routines *pApi) {SQLITE_EXTENSION_INIT2(pApi);
sqlite3pp:database db(sqlite3pp::ext::borrow(pdb));// pdb is not closed since db just borrows it.}

本文來自雲棲社群合作伙伴“開源中國”

本文作者：王練

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